A Fundamental Reactive Current Real-Time Detection Method Based on Direct Computation

For active power filter (APF), the study on fundamental reactive current detection method is necessary and has important meaning. In this paper, according to the Fourier seriespsila expression of the nonlinear load current, the detection principle of the fundamental reactive current is proposed. In terms of this detection principle, a fundamental reactive current real-time detection method based on direct computation is put forward. This method has the traits of using formula to calculate directly, small computation quantity, the variation of the electrical source frequency having very small influence, etc. When the load current is placed in stable state, the method can accurately calculate out the fundamental reactive current. When the load current slowly varies, the method has preferable tracking capability. When the load current takes a step change, the method has biggish computation error. When the load current is placed in mutative state, the amplitude of fundamental reactive current calculated out by the method can smoothly slowly circuitously track the true amplitude of fundamental reactive current. The correctness of the method is verified by both simulation and experiment.